JPH0633382Y2 - Battery operated electronic scale - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to an electronic scale using a battery as a power source,
The present invention relates to a battery-powered electronic scale that incorporates a variable capacitor whose capacity changes according to weight into an oscillation circuit and measures the weight of an object based on the frequency from the oscillation circuit.

<Prior Art> An electronic scale using a battery has an advantage that it can be easily carried and that an object can be weighed in a place without a commercial power source.

The conventional electronic balance using a battery mainly uses a variable capacitance capacitor whose electrostatic capacity changes due to weight from the viewpoint of low power consumption. And
In addition to improving measurement accuracy and reducing battery consumption, we are developing an electronic scale that uses a lower power supply voltage and uses fewer batteries.

FIG. 5 shows a conventional battery-powered electronic scale, in which an indicator (2) and a power switch (3) are provided on the surface of the casing, and a saucer (4) for mounting an object is attached to the opening of the casing. ing. An oscillation circuit (81) incorporating a variable capacitor (6), which is connected to the saucer (4) and whose electric capacity changes according to the displacement of the saucer (4), and the oscillation circuit A microprocessor that calculates weight based on the frequency of the output signal from (81) (8
4) and the oscillation circuit (8
1), microprocessor (84), and indicator (2)
And a dry battery (85) connected to (see FIG. 6).

In the electronic balance having the above structure, when the object is placed on the pan (4), the capacitance of the variable capacitor (6) changes according to the weight of the object. The oscillation frequency of the oscillation circuit (81) changes with the change in the electrostatic capacitance. Then, the microprocessor (84) counts the oscillation frequency and performs arithmetic processing based on the frequency,
The weight of the object is calculated, and the calculation result is displayed on the display (2).

<Problems to be Solved by the Invention> In the above electronic balance, in order to improve the measurement accuracy, it can be achieved by increasing the frequency of the output signal of the oscillation circuit. 84) It is necessary to shorten the cycle time. However, since the microprocessor with a fast cycle time consumes a large amount of power and has a high potential, the number of batteries to be used also increases, which causes a problem of cost increase.

More specifically, the cycle time of commercially available microprocessors that can be driven by 3V batteries is at most 12 times.
Since it is about 5 μsec, the oscillation frequency is set to 5 kHz or less and counting is performed, and a predetermined calculation is performed during the remaining time to count the weight of the measured object. Therefore, in the electronic scale having the above configuration,
There is a limit in measurement accuracy and power consumption.

<Purpose> The present invention has been made in view of the above problems, and an object thereof is to provide a battery-powered electronic balance that improves measurement accuracy and achieves reduction in power consumption.

<Means for Solving Problems> In order to achieve the above object, the battery-powered electronic balance of the present invention is
Use a dry battery or secondary battery and a solar battery as a power source, and measure the weight of an object based on the frequency from an oscillation circuit that incorporates a variable capacitor whose electrostatic capacity changes according to the weight. In the electronic scale described above, the oscillation circuit is connected to the solar cell, a counter for counting the frequency from the oscillation circuit, and a calculation for performing a predetermined calculation based on the output signal from the counter to measure the weight of the object. The processing device is characterized by being connected to the battery.

<Operation> In the battery-operated electronic balance of the present invention as described above, the counter is caused to count the frequency that requires the most cycle time, and the arithmetic processing unit determines the predetermined frequency based on the output signal from the counter. Since only the arithmetic processing is performed, the arithmetic processing time of the arithmetic processing device can be shortened and the power consumption of the arithmetic processing device can be reduced.

More specifically, the counter is a commercially available counter for low voltage, for example, even if the driving potential is about 3 V, it is possible to count the frequency of several tens of kHz, so even if the frequency of the oscillation circuit is increased, can do. Then, in the arithmetic processing device, by measuring the weight of the object by multiplying the output signal from the counter, that is, the counting result by a predetermined coefficient, the measurement accuracy can be improved.

In addition, since the solar cell is connected to the oscillation circuit, by constantly driving the oscillation circuit with a relatively slow rising speed with a solar cell with a physically stable potential, measurement errors after power-on can be avoided. You can almost eliminate it.

Further, also in the case where the arithmetic processing device measures the weight based on the difference between the output signals from the counter before mounting the measured object and after mounting the measured object, the same operation as above can be achieved.

Also, the battery consumption can be kept low by properly using the battery and the solar cell.

Further, even when the power source is a solar battery and a secondary battery connected, since the power consumption of the electronic scale is small, the secondary battery is only slightly charged by the solar battery, and the same operation as described above is performed. Can be achieved.

<Examples> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating examples.
The same parts as those in the conventional example are designated by the same reference numerals.

FIG. 1 shows a battery-powered electronic scale as an embodiment of the present invention, in which a solar cell (1), an indicator (2), and a power switch (3) are provided at predetermined positions on the surface of the casing, and the upper part of the casing is provided. A saucer (4) is attached to the opening. And
Inside the casing, a leaf spring (5) whose peripheral edge is fixed to a step inside the casing, a variable capacitor (6) whose electrostatic capacity changes according to the deflection of the leaf spring (5), and a saucer (4 ) And the leaf spring (5) and between the leaf spring (5) and the variable capacitance capacitor (6), and the struts (7) and (7 ') interposed, and the variable capacitance capacitor (6). And a weight measuring device (8) for measuring the weight of the object on the basis of the change in capacitance.

The variable capacitor (6) has a pair of electrodes (61).
(62), one electrode (61) is attached to the leaf spring (5) through the support (7), and the other electrode (62) is fixed to the bottom surface of the casing. Then, as the leaf spring (5) bends, one electrode (61) is displaced,
The capacitance increases as the distance between the electrodes (61) (62) decreases.

The structure of the weight measuring device (8) will be described with reference to the block diagram of FIG. 2. (81), two-input AND gate (82), counter (83), the two-input AND gate (82) and the counter (83) are controlled, and the object based on the output signal from the counter (83) A microprocessor (84) for calculating the weight of the product and displaying the calculation result on the display (2)
And a dry battery (85) having one electrode connected to the ground side of the solar cell (1) and the other electrode connected to the power switch (3).

The weight measuring device (8) will be described in more detail with reference to the circuit diagram of the oscillation circuit of FIG. 3 and the timing chart of FIG. A multivibrator is used in which a capacitor (6) and a resistor (8R) are connected to an amplifier element (8A) that consumes very little power. 2-input AND gate (82)
Is an output signal (see FIG. 4A) from the oscillation circuit (81) and a time control signal (see FIG. 4B) from the microprocessor (84), and an oscillation signal (within a predetermined time) ( (See FIG. 4C). The counter (83) is 2
The output signal from the input AND gate (82) is input as a clock, and the signal (see FIG. 4D) from the microprocessor (84) is used as a reset input.
The number of pulses of the output signal from 2) is counted.

Explaining the operation of the electronic scale, the oscillation circuit (81)
Is always connected to the solar cell (1), and since this solar cell (1) is a stable power source whose electric potential is physically determined, it outputs a signal of a constant frequency when no object is placed. is doing.

Next, turn on the power switch (3) to receive the object (4)
When placed on, the leaf spring (5) bends in accordance with the weight of the object, the upper electrode (61) of the variable capacitor (6) is displaced downward, and the space between the electrodes (61) (62) is reduced. The capacitance increases as the distance becomes shorter. As the capacitance increases, the oscillation frequency of the oscillator circuit (81) decreases (see Φ _{2 in} FIG. 4C). And a 2-input AND gate (8
In 2), the oscillation signal input within the time controlled by the microprocessor (84) is passed, and in the counter (83), the number of pulses of the output signal from the 2-input AND gate (82) is counted. . Then, in the microprocessor, arithmetic processing is performed based on the difference between the count output signals from the counter (83) before mounting the measurement object (oscillation frequency; Φ ₁ ) and after mounting the measurement object (oscillation frequency; Φ ₂ ). Is calculated, and the calculation result is displayed on the display (2).

In the above cases, the weight measurement accuracy of the object depends on the height of the frequency of the output signal from the oscillator circuit, and the reference frequency is to reduce the size of the resistor (8R) of the oscillator circuit (81). Can be adjusted higher. The counter (83), which has a high counting speed even if the potential is low,
Since the number of output pulses from the oscillation circuit (81) that is output at a predetermined time via the input AND gate (82) is counted, the oscillation circuit is generated by the microprocessor (84) like a conventional electronic scale. As compared with the case of directly counting the output pulse from (81), a higher frequency can be counted, and the measurement accuracy is greatly improved. In addition, by increasing the frequency of the oscillator circuit (81), the frequency change from the state in which no object is placed (highest frequency state) to the state in which an object is placed (lowest frequency state) The width can be widened and the measurement allowable range can be expanded.

Moreover, the microprocessor (84) has a counter (83)
Since only the weight of the object is calculated based on the counting result from, most of the cycle time can be devoted to arithmetic processing, so other processing associated with the lightweight of the object, such as processing such as charge conversion, can be performed. Will be possible.

In summary, the oscillating circuit (81) is connected to the solar cell (1), the oscillating circuit (81) is kept in a standby state, and an object is placed on the saucer (4). ), The oscillation frequency changes accurately according to the change in capacitance. And the oscillation frequency of the microprocessor (84)
Counting is performed by a counter (83) having a faster counting speed, and the microprocessor (84) measures the weight of the object based on the counting result from the counter (83) to improve the measurement accuracy in the use of the low potential dry battery. ing.

Incidentally, the present invention is not limited to the above embodiment, for example, a secondary battery is used instead of the dry battery (85),
Charging the secondary battery with the solar cell (1),
It is possible to replace the variable capacitor (6) with a variable air gap type that displaces between the electrode plates, and use a variable dielectric constant type in which a dielectric is inserted between the electrode plates. It is possible to make various design changes within the range where is not changed.

<Effect of Device> As described above, according to the battery-powered electronic balance of the present invention, the frequency that requires the most cycle time is counted by the counter having a faster counting speed than the microprocessor, and the measurement accuracy is improved. Since the arithmetic processing unit is caused to perform only predetermined arithmetic processing based on the output signal from the counter, the arithmetic processing time of the arithmetic processing unit is shortened,
The burden is lightened, and the power consumption of the arithmetic processing unit can be reduced.

Moreover, since the solar cell is connected to the oscillating circuit, the oscillating circuit having a relatively slow rising speed can be always driven, and an electronic scale having almost no measurement error after power-on can be realized.

Also, the battery consumption can be kept low by properly using the battery and the solar cell.

Therefore, the practicable effect peculiar to the improvement of the measurement accuracy and the reduction of the power consumption can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view and a schematic view of a battery-powered electronic balance as an embodiment of the present invention, FIG. 2 is a block diagram of the embodiment of FIG. 1, and FIG. 3 shows details of the oscillation circuit of FIG. FIG. 4 is a timing chart, FIG. 5 is a perspective view of a conventional battery-powered electronic scale, and FIG. 6 is a block diagram of a conventional battery-powered electronic scale. (3) …… Power switch, (6) …… Variable capacitor, (81) …… Oscillation circuit, (83) …… Counter, (84) …… Microprocessor, (85) …… Dry battery.

Claims (1)

[Scope of utility model registration request] 1. A weight of an object based on a frequency from an oscillating circuit, which uses a battery composed of a dry battery or a secondary battery and a solar battery as a power source and incorporates a variable capacitor whose electrostatic capacity changes according to a weight. In an electronic scale adapted to measure, the oscillation circuit is connected to the solar cell, a counter for counting the frequency from the oscillation circuit,
A battery-operated electronic scale characterized by being connected to the above-mentioned battery and an arithmetic processing unit for performing a predetermined arithmetic operation based on an output signal from a counter to measure the weight of an object.